• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.4
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• pp.819-830
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• 2017

An FM radio based PCL system is a passive radar technique for detecting the multiple moving targets from FM radio signals and tracking the trajectories of the targets by calculating the cross-correlation function of direct-path signal and target echo signals. However, the interference signals are received from a surveillance channel, which is designed to receive the target echo signals. Because of this problem, the target echo signals are masked by the strong interference signals and this makes it difficult to detect the true targets from the cross-correlation function. Adaptive filters are known as effective methods for suppressing the interference signals but there is a problem to present their accurate performances in the PCL system because many literatures used the cross-correlation function and the ratio of input and output power as a measure of the performance analysis. In this paper, a performance analysis method is proposed to evaluate the performance of interference cancellation algorithms. By using the property that each component of the filter weight vector is adjusted to suppress the specific interference signal, a performance measure of the interference signal suppression is defined by a function of adaptive filter weights. Based on the proposed method, we compare the performance of the adaptive filters used in the PCL system. Simulation results show that the proposed method can be very effective for evaluating the performance of interference cancellation algorithms.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.8
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• pp.1752-1758
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• 2010

A FM-CW radar is used for the various purposes as a remote sensing device since it has the advantages of the relatively simple implementation and the low probability of signal interception. A FM-CW radar uses the same frequency modulated continuous wave for both transmission and demodulation. Therefore, the received beat frequency represents the range and Doppler information of targets. However, using the conventional FFT method, the degree of accuracy and resolution in the spectrum estimation can be seriously degraded in the detection and tracking of fast moving targets because of the short dwell time. Therefore, in this paper, the model parameter estimation methods called as an autoregressive method is applied to overcome these problems and showed that the improved accuracy and resolution can be obtained for the target range and velocity estimation.

• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2650-2652
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• 1999

To satisfy the demand for small size, light weight. high density power supply, the switching frequency of DC/DC converters has been increased. The PWM control of the conventional SMPS have a switching frequency that a level of the conducted noise spectra contribute to switching frequency band. So the electronic equipment is not only affected from that but is restricted to internal regulation like CISPR, FCC, and VDE. In this paper, we analyzed Bi-FM. Bi-FM is two fixed switching frequency with a modulation frequency. So emission spectrum of Bi-FM control signal is spreaded and spectral power level is reduced. In this paper, we analyze the spectral analysis of Bi-FM control signal and the spectral comparison between the PWM control and Bi-FM control. And we confirm that reduced the spectrum power level through simulation using Pspice and experiment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.6
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• pp.572-579
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• 1992

In this thesis, feedback circuit and FM detector applied to superheterodyne receiver to extract audio signal without random noise Is implemented. The feedback loop circuit converts 45MHz received signal to 4SiKHz If signal containing mess-age without random noise. Also the feedback loop provides the End local frequency, so narrowband BPF which is containing maximum Doppler frequency without message Is needed. Finally, quadrature FM detector extract audio signal by synthesis o350" shifted signal and ampli-tude limited signal. RSSI characteristics is measured and audio characteristics Is compared with existing If module.

• Speech Sciences
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• v.12 no.4
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• pp.53-70
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• 2005

A Vowel of speech signals are multicomponent signals composed of AM-FM components whose instantaneous frequency and instantaneous amplitude are time-varying. The changes of emotion states cause the variation of the instantaneous frequencies and the instantaneous amplitudes of AM-FM components. Therefore, it is important to estimate exactly the instantaneous frequencies and the instantaneous amplitudes of AM-FM components for the extraction of key information representing emotion states and changes in speech signals. In tills paper, firstly a method decomposing speech signals into AM - FM components is addressed. Secondly, the fundamental frequency of vowel sound is estimated by the simple method based on the spectrogram. The estimate of the fundamental frequency is used for decomposing speech signals into AM-FM components. Thirdly, an estimation method is suggested for separation of the instantaneous frequencies and the instantaneous amplitudes of the decomposed AM - FM components, based on Hilbert transform and the demodulation property of the extended Fourier transform. The estimates of the instantaneous frequencies and the instantaneous amplitudes can be used for modification of the spectral distribution and smooth connection of two words in the speech synthesis systems based on a corpus.

• Korean Journal of Environment and Ecology
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• v.24 no.2
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• pp.202-208
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• 2010

This study reports developmental changes in the vocal signals produced by infant or young Pipistrellus abramus. In contrast to adult bats, infant bats of the P. abramus emitted calls characterized by multi harmonics and variable signal patterns. Infants at two day of age emitted a irregular signal and showed gentle FM signals between 10 and 20 days. After about 40 days of age, the young bats emitted similar signals to the echolocation calls of adults. As the infant bats growing up, vocal signals trend showen a decrease in pulse duration(p<0.001), pulse interval(p<0.001) and number of harmonic(p<0.001). And the peak frequency(p<0.001), starting frequency(p<0.001) and ending frequency(p<0.001) in infant bats increased with the age. The largest change in pulse interval occurred in 5 days. And the pulse duration, peak frequency, starting frequency and ending frequency of the bat's sounds changed most dramatically in 25 days of age.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.5
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• pp.18-23
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• 1998

Development of an automobile antenna printed on-glass for FM radio receptions was discussed in this study. NEC-2 code was used as the design tool in this research. An omnidirectional radiation pattern and reception power level of the newly designed antenna were compared with those of the conventional pole antenna for the evaluation of its performance. The test sites for the reception power level measurement were chosen by their signal enbironmental condition, such as multipath fading, and strong field effect area.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.167-170
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• 1995

An frequency modulated (FM) DANTE pulse sequence generates a quadratic phase toward the transverse of image by an FM RF pulse. In the image of a serious susceptibility effect, the phase due to the difference of the susceptibility in the pixel occurs susceptibility error which arise signal loss. But the signal loss due to the susceptibility effect in the pixel is reduced when the quadratic phase adds in the pixel. In this paper, we have generated a quadratic function toward the transverse (X-Y) using FM DANTE sequence and the susceptibility effect is reduced in the gradient echo (GE) imaging. Computer simulation and experimental results is obtained by using a whole-body KAIS 2.0T NMR system.

• Speech Sciences
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• v.12 no.4
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• pp.17-29
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• 2005

Time-frequency representation reveals some useful information about instantaneous frequency, instantaneous bandwidth and boundary of each AM-FM component of a speech signal. In many cases, the instantaneous frequency of each component is not constant. The variability of instantaneous frequency causes degradation of resolution in time-frequency representation. This paper presents a method of adaptively adjusting the transform kernel for preventing degradation of resolution due to time-varying instantaneous frequency. The transform kernel is the form of frequency modulated function. The modulation function in the transform kernel is determined by the estimate of instantaneous frequency which is approximated by first order polynomial at each time instance. Also, the window function is modulated by the estimated instantaneous. frequency for mitigation of fringing. effect. In the proposed method, not only the transform kernel but also the shape and the length of. the window function are adaptively adjusted by the instantaneous frequency of a speech signal.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.338-341
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• 2013

본 논문에서는 동일 주파수 대역 내 DRM(Digital Radio Mondiale) Plus 신호와 FM(Frequeny Modulation) 신호가 모두 서비스 되는 Hybrid 방송 모드에 적합한 DRM Plus 신호 검출 기법을 제안한다. OFDM(Orthogonal Frequency Division Multiplexing) 신호의 Guard-Interval 상관 기법을 그대로 적용할 경우 DRM Plus 신호 검출 성능은 우수하나, FM 신호 수신 시 False Alarm 발생 확률이 증가하는 문제점이 발생한다. 제안한 방법은 Guard-Interval 상관 방법에 Reference 블록을 포함하고 있어, 약한 DRM Plus 신호에서도 판별 확률이 높고, 아날로그 FM 신호 수신 시 False Alarm이 발생할 확률이 낮은 특징이 있다. 모의 실험을 통하여 제안한 기법의 성능을 확인한다.